Usage

Versions

The Rand lib is not yet stable, however we are careful to limit breaking changes
and warn via deprecation wherever possible. Patch versions never introduce
breaking changes. The following minor versions are supported:

Version 0.6 was released in November 2018, redesigning the seq module,
moving most PRNGs to external crates, and many small changes.

Version 0.5 was released in May 2018, as a major reorganisation
(introducing RngCore and rand_core, and deprecating Rand and the
previous distribution traits).

Version 0.4 was released in December 2017, but contained almost no breaking
changes from the 0.3 series.

When upgrading to the next minor series (especially 0.4 → 0.5), we recommend
reading the Upgrade Guide.

Rust version requirements

Since version 0.5, Rand requires Rustc version 1.22 or greater.
Rand 0.4 and 0.3 (since approx. June 2017) require Rustc version 1.15 or
greater. Subsets of the Rand code may work with older Rust versions, but this
is not supported.

Travis CI always has a build with a pinned version of Rustc matching the oldest
supported Rust release. The current policy is that this can be updated in any
Rand release if required, but the change must be noted in the changelog.

To avoid bumping the required version unnecessarily, we use a build.rs script
to auto-detect the compiler version and enable certain features or change code
paths automatically. Since this makes it easy to unintentionally make use of
features requiring a more recent Rust version, we recommend testing with a
pinned version of Rustc if you require compatibility with a specific version.

Crate Features

Rand is built with the std and rand_os features enabled by default:

std enables functionality dependent on the std lib and implies alloc
and rand_os

rand_os enables the rand_os crate, rngs::OsRng and enables its usage;
the continued existance of this feature is not guaranteed so users are
encouraged to specify std instead